Manufacture of esters



Oct. l2, 1937. w. P. GERG 2,095,496

MANUFACTURE OF ESTERS Filed Jan. 9, 1935 Q Z7 INVENTOR WILL/AM G's/ea.

ATTORNEY.

'-' have endeavored Patented Oct. 12, 1937 OFFICE MANUFACTURE OF ESTERS William P. Gerg, Oadosia,

Inc Hancock, N. Y.

Thomas Kcery Co.

N. Y., assignor to Application January 9, 1935, Serial No. 1,014

3 Claims.

My invention relates'to the manufacture of esters and has for its principal object the provision of a means and method of producing esters directly from taining soluble tar.

In general practice the production of esters from pyroligneous liquor has'been to first treat the liquor toremove the soluble tar and the hydrocarbons therefrom and to use onlythe remaining acid, thus substantially refined, in the production of; the esters. A necessitated additional and more or less expensive steps and apparatus and'has resulted in waste amass. ,Iam also aware that others to produce esters directly from the wood distillate in a continuous process but that such efforts have not proven practical for pyroligneous liquor still conthe reason that no adequate means have been' provided for separating and removing the tar' f rom'the' liquor in such a manner as to prevent its coking and adhering to the walls and parts oflthe' apparatus in a manner toquickly reduce their efliciency and thus necessitating frequent delays in' the process for dimcult and expensive cleaning operations. s r

"By, my invention I have provided a means whereby the wood distillate or liquor, still containing soluble tar, Wood oils, and hydrocarbons may be used in the production of esters without preliminary treatment and without danger of interfering with the continuous operation of the system because of the coking or improper separation'or removal of these elements of the liquor. One important object and advantage of my invention lies in the provision of a better contact between the acid in the liquor and the alco-,

hol used therewith, whereby a better yield of the desired ester is possible, both quantitively and qualitivelya Another object and advantage lies in the provision of a' relatively high speed removal'of the vapors from the generating equipment which results in better yield.

Oneaof the most important objects and advantages lies in ameans' and method of continuously concentrating the soluble wood oils and'tars from the liquor, resulting in the prevention of the hardening or coking of the unsaturated hydrocarbons and thus preventing stoppage of the process and making possible the maintenance of the equipment at high efiiciency. I A further object and'advantage lies in maintaining the hydrocarbon and wood oil residue of such small volume at any given time that Obviously this has I is mixed. The tanks l and 2 v common supply'line 6 for it can be more quickly and easily, as well as economically, removed.

Still another object consists in the use of relatively small sized ester generating equipment which results in the more effective breaking down of the impurities by the catalyst, the catalyst being most efiective when used with relatively small units of the acid and alcohol.

A further object lies in the obtaining of improved results bythe use of a relatively small 10 amount of catalyst as compared with the ordinary process, thus rendering my method more economical. r

Although I have illustrated and will describe my invention as utilized in the production of methyl acetate,it will be understood that this is intended as illustrative only for it will be apparent that the invention is equally adaptable for the production of other esters as well.

Other objects and advantages will be apparent as the description proceeds, reference now being had to the figure of the accompanying drawing forming a part of this application, and wherein like reference numerals indicate like parts.

In the drawing:

. Figure 1 is a diagrammatic figure of a suitable apparatus illustrating the steps by which my invention may be carried out. 7 a

The details of the apparatus have not been illustrated as they form no part of this invention. It will be understood that desired and the dilferent steps of the process.

The reference character I indicates generally a supply tank for the pyroligneous liquor which, as before explained, is the direct wood distillate without preliminary treatment to remove the tar, wood oils, and hydrocarbons. The reference character 2 indicates a supply tank for the natural alcohol with which the liquor from the tank are provided with flow gauge cylinders 3 and gauges 4. From the cylinders 3 the liquor and alcohol flow in measured amounts through the float boxes 5 to a common supply pipe 6, control valves 1 being provided between the float boxes 5 and the regulating the now of the liquor and alcohol. Although the proportions of the liquor and alcohol may vary in accordance with the product being produced and in accordance with other requirements of the process, it has been found in practical use in the manufacture of methyl acetate that a 5' small supply receptacle proportion of 60% of liquor and 40% of alcohol produces good results.

The measured mixture of liquor and alcohol is flowed or pumped into a heater tank H and into the conventional tubes therein, well known in the construction of calandria heaters.

Steam is applied to the tank H adjacent the top thereof, by means of the steam line 8, such line being controlled by the valve 3 therein. The steam enters the tank around the outside of the tubes therein, heating the same to a high temperature and causing the liquor and alcohol therein to boil off at the top of the tubes. The steam condensate is drawn off adjacent the lower end of the tank as at II], the valve II being provided for regulating the flow thereof. This condensate is then returned through suitable means to the boiler or heater (not shown) supplying the steam.

The boiling liquid composed of the liquor and alcohol passes from the top of the tubes within the tank H through a conduit I2 to a relatively small expansion still I3 within which the alcohol, the esters, and some Water and acid, vaporize. A

I4 is provided for a suit.- able catalyst such as sulphuric acid and this catalyst, passing through a suitable conduit I5, enters the expansion still I3 adjacent the top thereof where it joins the boiling liquid and vapors therein. In the process of distillation within the still I3, the higher boilers including the tar, catalyst, hydrocarbons, wood oils, and a portion of water and acids, are drawrroff fromthe bottom of the still I3 through the conduit, I6,

' a valve I"I being provided in this line to regulate the flow thereof. These condensedmaterialsare returned by the conduit It to the inlet of the heater tank H where they are mixed with the incoming new liquor and alcohol entering the tubes of such tank.

It will be clear that due to the relatively small amount of the liquid being processed in the expansion still I3 at any given time, only a small amount of catalyst is required. This is an important feature inasmuch as the catalyst is more effective with, small units of the. liquor and alcohol.

The vaporized alcohol, esters, and water, together with a trace of acid, pass from the. top of the expansion still I3 into the ester concentrating column I8. In practice it has been found effective to deliver these vapors to the concentrating column I8 at a point spaced above the bottom of the column corresponding to approximately the 5th plate above bottom. The plates are indicated at I9 and have not been shown in detail as they may be of well known or desired construction and form no part of, this invention. The delivery of the vapors to the concentrating column I8 is effected through the conduit leading from the top of the expansion still I3. As the vapors rise in the column I8 they condense upon the boiling points of the different materials. The condensate, now consisting of water and methyl alcohol carrying some woodoils, dropping to the bottom of the concentrating column I8, pass therefrom through the conduit EI- and is delivered to a rectifying column 22. In practice it has been found that best results are obtained by delivering this condensate to'the rectifying column 22 at a point approximating the 13th plate of this column. Here again the plates 23 have not been shown in any detail at different levels, depending as they are of conventional or desired construction and form no part of this invention.

Steam is applied to the bottom of the rectifying tank or column 22 through the conduit 24 controlled by the valve 25 therein. 'The water condensate, carrying some wood oils, is exhausted from the rectifying column 22 by the steam entering the same as described, such exhaust being through the conduit 26 controlledby the valve 21.

The steam entering this rectifying column 22 heats the same and vaporizes the alcohol and the small amount of esters carried thereby. These vapors rise to the top of the column and pass to a suitable condenser 28 through the conduit 29. The condensate from the condenser 28 passes through the conduit 30 and a portion of it is returned through the conduit 3I to the original common supply pipe 6 and a portion of it is returned again to the top of the rectifying column 22 through the conduit 32 where it again vaporizes and passes to the condenser 28.

The vapors from the concentrating column I8,

after rectification and concentration therein pass from the top of the column through the conduit 33 to a suitable dephlegmator 34 and then through the conduit 35 to the condenser 36. From the condenser 36 the methyl acetate, or other ester being produced, may be withdrawn through the conduit 38.

34 and a portion of .the condensate from the condenser 36 are taken through the reflux conduits 33 and 48 and returned centrating column I8 whereby to balance the quality of the delivered product.

The delivered ester from the condenser 36 is of high quality and ready for immediate commercial use.

Although by the use of the method andv appa ratus units described, this process of .producing an ester directly and continuously from pyroligneous liquor without previous treatment and still con taining soluble tar, hydrocarbons, and wood oil's, substantially eliminates the hardening or coking of the tar and hydrocarbons in the various units of equipment, and particularly in the. heaterfH, the expansion still I3 and the concentrating column I8, it may be occasionally desirable to clean outthese units and remove any collected substances therefrom or it may be desirable to clean them out in preparation for using for other material and processes. For this purpose I have provided an outlet conduit II controlled by a valve 42, at the bottom of the heater tank H, through which such collected solids and. liquids may be pumped and thus withdrawn. This may, if desired, be done during the processing without interference with the generation of the ester.

Emphasis is again placed upon the importance of the relatively small heater unit H and expansion still I3 comprising the ester generating units which permits the very effectivecontinuous concentrating and breaking down of the impurities in the pyroligneous liquor bythe catalyst and the continuous circulation of the condensate fromthe still I3 through the heater, together with the fresh liquor and alcohol'. This effectively pre vents the coking of the tar; and hydrocarbonsin the apparatus and makespossible the continued use thereof in the directproduction of the ester from the pyroligneousliquor or wood distillate.

Of course, changes may be made in details without departing from the spiritand scope of my invention. I do not limit myself, ,therefore,

31 controlled by the valve A portion of vapor from the dephlegmator to the top-of the con;

the equipment ing the steps of boiling to the exact form herein shown and described other than by the appended claims.

I claim:

1. The process of manufacturing an ester diroot from unrefined pyroligneous liquor comprisa mixture of the liquor and alcohol, passing the boiling mixture into an expansion still where anacid catalyzer, adapted to break down the impurities of the liquor, is added passing the vapors from said still to concentrating column and has been condensed in the expansion still, together with said catalyzer, back to said mixture of liquor and alcohol for reboiling therewith, and condensing the ester from the vapors from said concentrating column. r

2. The process of manufacturing an ester di- 7 rect from unrefined pyroligneous liquor comprising the steps of boiling a mixture of the liquor and alcohol, passing the boiling mixture into an expansion still of restricted size to limit the amount of liquid therein at one time, adding an acid catalyzer, adapted to break down the impurities of the liquor, to said liquid in said still, passing the vapors from said still to a concentrating column and passing the liquid which has been passing the liquid which condensed insaid expansion still back to said mixture of liquor and alcohol for reboiling therewith, and condensing the ester from the vapors from said concentrating column.

3. The process of manufacturing an ester direct from unrefined pyroligneous liquor comprising the steps of boiling a mixture of the liquor and alcohol, passing the boiling mixture into an expansion still of restricted size to limit the amount of liquid therein at one time, adding an acid catalyzer, adapted to break down the impurities of the liquor, to said liquid in said still, passing the vapors from said still to a concentrating column and passing the liquid which has been condensed in said expansion still together with said catalyzer back to said mixture of liquor and alcohol for reboiling therewith, condensing the ester from the vapors from said concentrating column, and passing the condensate from the concentrating column to an exhausting column, the condensate of which latter column is removed and the vapors from said exhausting column being rectified, condensed and returned to said mixture of liquor and alcohol.

WILLIAM P. GERG. 

